1. Field of the Invention
The present invention relates to a server and, in particular, to a technique for controlling access to information stored in a server (hereinafter called server information).
2. Description of the Related Art
In recent years, a world wide web (WWW) system has been spread in which a signal (uniform resource locator: URL) requesting user's desired server information (contents) is sent from a client to a server and the server transmits the required server information to the client.
In such a system, in the case of limiting a user's access to the server information, the access control function of an operating system (OS) operated on the server is usually utilized. For example, when the attribute of a file in which server information is recorded is set so as not to be able to be read by a certain user, the user can not receive the file from the server even if a signal requesting the server information recorded in the file is sent from the client to the server. In this manner, it is easily performed to limit a predetermined user's access to the server information by utilizing the access control function of the OS.
However, according to such a technique, each of users can not be determined as to whether or not the each user has access right to server information based on the access control until the each user actually accesses the server information. Accordingly, when server information includes many link information each linked to server information to which a user has no access right, the user is obliged to repeatedly and wastefully access to server information, whereby there arise a problem that the user must waste time upon accessing.
In most cases, the server information to which some users have no access right is generally important data. According to the aforesaid technique, at least the presence of the server information to which the access right is not permitted is known to the users. Thus, some of the users may illegally try to access the server to which the access right is not permitted at any cost.
One of general techniques for controlling the access to a file is a file management method disclosed in JP-A 4-280317. According to this method, when a user has no access right to a file, an icon corresponding to the file is not displayed on a display device. Thus, according to this technique, the presence of a file to which a user has no access right can be concealed from the user.
However, when such a method is applied as it is to a distributing system of hyper link information such as a WWW system, even if the presence of other hyper link information can be concealed, display information to be generated from the original hyper link information is reduced. As a consequence, there arises a problem that all information originally intended by a person who prepared the server information can not be transmitted from a server.